The optical waveguide element has a first optical waveguide core; and a second optical waveguide core. In the optical waveguide element, the first optical waveguide core includes a first coupling portion configured to propagate any one polarized wave of a TE polarized wave and a TM polarized wave of a k.sup.th-order mode, the other polarized wave of an h.sup.th-order mode, and the other polarized wave of a p.sup.th-order mode, and a first Bragg reflector connected to the first coupling portion. The second optical waveguide core includes a second coupling portion. The first Bragg reflector includes a rib waveguide including a grating configured to convert the one input polarized wave of the k.sup.th-order mode into the other polarized wave of the h.sup.th-order mode, reflect the converted polarized wave on the basis of Bragg reflection, and transmit the other input polarized wave of the p.sup.th-order mode, and slab waveguides having thicknesses smaller than that of the rib waveguide and integrally formed with the rib waveguide on both side surfaces of the rib waveguide respectively, in the light propagation direction.

Compact photonics platforms and methods of forming the same are provided. An example of a compact photonics platform includes a layered structure having an active region along a longitudinal axis, a facet having an angle no less than a critical angle formed at at least one longitudinal end of the active region, and a waveguide having at least one grating coupler positioned in alignment with the angled facet to couple light out to or in from the waveguide.

An optical device fabrication method includes removing semiconductor material from a semiconductor substrate to form a first curved surface and a second curved surface, forming a bonding material on the first curved surface, and selectively removing semiconductor material from at least one of the first and the second curved surfaces to form one or more subwavelength structures. The semiconductor substrate has a bandgap wavelength associated with a bandgap energy of the semiconductor material. The optical device refracts certain incident electromagnetic radiation and/or filters other electromagnetic radiation. The refracted radiation includes infrared wavelengths longer than the bandgap wavelength and the filtered radiation includes wavelengths shorter than the bandgap wavelength.

An optical device fabrication method includes removing semiconductor material from a semiconductor substrate to form a first curved surface and a second curved surface, forming a bonding material on the first curved surface, and selectively removing semiconductor material from at least one of the first and the second curved surfaces to form one or more subwavelength structures. The semiconductor substrate has a bandgap wavelength associated with a bandgap energy of the semiconductor material. The optical device refracts certain incident electromagnetic radiation and/or filters other electromagnetic radiation. The refracted radiation includes infrared wavelengths longer than the bandgap wavelength and the filtered radiation includes wavelengths shorter than the bandgap wavelength.

An optical apparatus includes a diffractive optical element (DOE), having at least one optical surface, a side surface, which is not parallel to the at least one optical surface of the DOE, and a grating, which is formed on the at least one optical surface so as to receive and diffract first radiation that is incident on the grating. The apparatus further includes at least one secondary radiation source, which is configured to direct second radiation to impinge on the side surface, causing at least part of the second radiation to propagate within the DOE while diffracting internally from the grating and to exit through the side surface. The apparatus also includes at least one radiation detector, which is positioned so as to receive and sense an intensity of the second radiation that has exited through the side surface.

An optical apparatus includes a diffractive optical element (DOE), having at least one optical surface, a side surface, which is not parallel to the at least one optical surface of the DOE, and a grating, which is formed on the at least one optical surface so as to receive and diffract first radiation that is incident on the grating. The apparatus further includes at least one secondary radiation source, which is configured to direct second radiation to impinge on the side surface, causing at least part of the second radiation to propagate within the DOE while diffracting internally from the grating and to exit through the side surface. The apparatus also includes at least one radiation detector, which is positioned so as to receive and sense an intensity of the second radiation that has exited through the side surface.

A grating element includes: a support substrate; an optical material layer; a ridge optical waveguide having an incidence surface on which a laser light is incident and an emission end from which an emission light with a desired wavelength is emitted; and a Bragg grating including concave and convex portions formed within the optical waveguide. The optical waveguide includes an incident portion between the incidence surface and the Bragg grating, and a tapered portion between the incident portion and the Bragg grating. In the Bragg grating, a propagation light propagates in single mode. The width W.sub.in of the optical waveguide in the incident portion is larger than the width W.sub.gr of the optical waveguide in the Bragg grating. The width W.sub.t of the optical waveguide in the tapered portion is decreased from the incident portion toward the Bragg grating. The relationships represented by formulas (1) to (3) are satisfied.

A grating element includes: a support substrate; an optical material layer; a ridge optical waveguide having an incidence surface on which a laser light is incident and an emission end from which an emission light with a desired wavelength is emitted; and a Bragg grating including concave and convex portions formed within the optical waveguide. The optical waveguide includes an incident portion between the incidence surface and the Bragg grating, and a tapered portion between the incident portion and the Bragg grating. In the Bragg grating, a propagation light propagates in single mode. The width W.sub.in of the optical waveguide in the incident portion is larger than the width W.sub.gr of the optical waveguide in the Bragg grating. The width W.sub.t of the optical waveguide in the tapered portion is decreased from the incident portion toward the Bragg grating. The relationships represented by formulas (1) to (3) are satisfied.

A device includes a waveguide grating out-coupler, and a tunable uniform phase shifter communicating with the waveguide grating out-coupler. The tunable uniform phase shifter steers a flat phase front along a first angle in a first plane. Optionally, the waveguide grating out-coupler includes a modulated refractive index and a physical grating period. The tunable uniform phase shifter controls the refractive index, thereby controlling an effective grating period. The grating period relates to the modulated refractive index, and the physical grating period. Optionally, the tunable uniform phase shifter includes a first thermo-optic phase shifter, a first electro-optic phase shifter, or a first micro-electro-mechanical system index perturbation phase shifter. Optionally, the tunable linear gradient phase shifter communicates with the waveguide grating out-coupler and steers a beam along the flat phase front along a second angle in a second plane, which is perpendicular to the first plane.

A device includes a waveguide grating out-coupler, and a tunable uniform phase shifter communicating with the waveguide grating out-coupler. The tunable uniform phase shifter steers a flat phase front along a first angle in a first plane. Optionally, the waveguide grating out-coupler includes a modulated refractive index and a physical grating period. The tunable uniform phase shifter controls the refractive index, thereby controlling an effective grating period. The grating period relates to the modulated refractive index, and the physical grating period. Optionally, the tunable uniform phase shifter includes a first thermo-optic phase shifter, a first electro-optic phase shifter, or a first micro-electro-mechanical system index perturbation phase shifter. Optionally, the tunable linear gradient phase shifter communicates with the waveguide grating out-coupler and steers a beam along the flat phase front along a second angle in a second plane, which is perpendicular to the first plane.